What is the term for movement characterized by tossing and rolling in an uncontrolled manner?

The term that describes movement characterized by tossing and rolling in an uncontrolled manner is "welter." This word captures the chaotic and tumultuous nature of such movement, often associated with a sense of confusion and disorder. In various contexts, "welter" can refer to a disorganized mixture or an overwhelming state, emphasizing a lack of control and coherence.

The other options do not convey the same meaning. "Tumid" refers to something that is swollen or distended, lacking the connotation of disorder in movement. "Quiescence" describes a state of inactivity or dormancy, which is the opposite of movement. "Fatuous" means silly or foolish, which does not relate to the idea of physical movement at all. Therefore, "welter" is the only term that correctly encapsulates the described action.